( function () {

	/**
 * RGB Shift Shader
 * Shifts red and blue channels from center in opposite directions
 * Ported from http://kriss.cx/tom/2009/05/rgb-shift/
 * by Tom Butterworth / http://kriss.cx/tom/
 *
 * amount: shift distance (1 is width of input)
 * angle: shift angle in radians
 */
	const RGBShiftShader = {
		uniforms: {
			'tDiffuse': {
				value: null
			},
			'amount': {
				value: 0.005
			},
			'angle': {
				value: 0.0
			}
		},
		vertexShader:
  /* glsl */
  `

		varying vec2 vUv;

		void main() {

			vUv = uv;
			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

		}`,
		fragmentShader:
  /* glsl */
  `

		uniform sampler2D tDiffuse;
		uniform float amount;
		uniform float angle;

		varying vec2 vUv;

		void main() {

			vec2 offset = amount * vec2( cos(angle), sin(angle));
			vec4 cr = texture2D(tDiffuse, vUv + offset);
			vec4 cga = texture2D(tDiffuse, vUv);
			vec4 cb = texture2D(tDiffuse, vUv - offset);
			gl_FragColor = vec4(cr.r, cga.g, cb.b, cga.a);

		}`
	};

	THREE.RGBShiftShader = RGBShiftShader;

} )();
